All that I shall attempt here is to show that it does not do this any more than the risk of sense-illusion can be said materially to affect the value of external observation.
It is to be noted first of all that the errors of introspection are much more limited than those of sense-perception.

They broadly answer to the slight errors connected with the discrimination and recognition of the sense-impression.

There is nothing answering to a complete hallucination in the sphere of the inner mental life.

It follows, too, from what has been said above, that the amount of active error in introspection is insignificant, since the representation of a feeling or belief is so very similar to the actual experience of it.
In brief, the errors of introspection, though numerous, are all too slight to render the process of introspection as a whole unsound and untrustworthy.

Though, as we have seen, it involves, strictly speaking, an ingredient of representation, this fact does not do away with the broad distinction between presentative and representative cognition.
Introspection is presentative in the sense that the reality constituting the object of cognition, the mind's present feeling, is as directly present to the knowing mind as anything can be conceived to be.